Comparison of wild type and genetically engineered nuclear polyhedrosis viruses of Autographa californica for mortality, virus replication and polyhedra production in Trichoplusia ni larvae

Virus replication and polyhedra production of two polyhedron-positive recombinant nuclear polyhedrosis viruses of Autographa californica, AcJHE.KK and AcAaIT which encode juvenile hormone esterase and scorpion toxin, respectively, were compared with those of a plaque purified wild-type nuclear polyhedrosis virus, AcMNPV-C6, in Trichoplusia ni larvae. Though average times required to kill the T. ni larvae increased with the age of the larvae, killing time by either recombinant virus was significantly shorter than that by wild-type virus. Killing time was reduced ca. 30% for AcAaIT-infected larvae and 5 to 8% for AcJHE.KK-infected larvae as compared to that for AcMNPV-C6-infected larvae. The average weight of larvae infected with AcAaIT was significantly lower than that of larvae infected with AcJHE.KK and AcMNPV-C6. The mean numbers of polyhedra produced in each larva inoculated with AcAaIT and AcJHE.KK were ca. 20% and 60%, respectively, of those for AcMNPV-C6. Total virus titers in AcMNPV-C6-infected larvae were significantly higher than those in AcJHE.KK- and AcAaIT-infected larvae until 2 days post infection.     

Repeated transfer of small RNA virus populations leading to balanced fitness with infrequent stochastic drift

The population dynamics of RNA viruses have an important influence on fitness variation and, in consequence, on the adaptative potential and virulence of this ubiquitous group of pathogens. Earlier work with vesicular stomatitis virus showed that large population transfers were reproducibly associated with fitness increases, whereas repeated transfers from plaque to plaque (genetic bottlenecks) lead to losses in fitness. We demonstrate here that repeated five-plaque to five-plaque passage series yield long-term fitness stability, except for occasional stochastic fitness jumps. Repeated five-plaque passages regularly alternating with two consecutive large population transmissions did not cause fitness losses, but did limit the size of fitness gains that would otherwise have occurred. These results underscore the profound effects of bottleneck transmissions in virus evolution.     

Effects of Nerve Growth Factor and Phorbol Derivative on Reactivation of Herpes Simplex Virus Type 1 in Cultured Cells of Latently Infected Adult Mouse Trigeminal Ganglia

Reactivation of herpes simplex virus type 1 (HSV-1) occurred rapidly in cells of latently infected adult mouse trigeminal ganglia which were cultured in serum-free medium in the presence of sufficient nerve growth factor (NGF). However, HSV-1 reactivation was delayed significantly in ganglionic cultures in the absence of exogenous NGF or in cultures treated with 2-aminopurine in the presence of NGF. The delayed viral reactivation in ganglionic cultures without NGF was accelerated by treatment with phorbol myristate acetate or dibutyryl cyclic AMP. Culture conditions which affected HSV-1 reactivation did not affect replication of HSV-1 in normal ganglionic cultures.     

Augmentation of Interferon Production after Cell-Differentiation of U937 Cells by TPA

Persistent infections with mumps virus were established in several human lymphoid cells of T-cell origin (Molt-4, TALL-1, and CCRF-CEM) and human monocyte cells (U937 and THP-1). 2′,5′-Oligoadenylate synthetase (2–5AS) activity was demonstrated to be only slightly induced by interferon (IFN) or TPA (12-O-tetradecanoyl-phorbol-13-acetate) treatment in these cells. Treatment of the persistently infected cells with IFN or TPA did not stimulate an increase in the amount of synthetase mRNA. Induction of cell differentiation and augmentation of IFN production by TPA were demonstrated in U937 cells persistently infected with mumps virus (U937-MP). Similar results for IFN production were obtained from differentiated U937 cells. It is suggested that cell differentiation of U937 cells might be associated with the development of IFN inducibility.     

Proliferation and Teratogenicity of Aino Virus in Chick Embryos

Aino virus (AIV; JaNAr 28 strain) 10³ TCID₅₀/0.2 ml was inoculated in the yolk sac of 8-day-old chick embryos. Recovery and titration of the virus from various organs including the central nervous system (CNS) and skeletal muscle were performed at 2, 4, 7, 10 and 13 days after inoculation (PI). AIV was systemically disseminated and proliferated even 2 days PI. The titers of the recovered virus from the CNS and from skeletal muscle was the highest at 4 days PI and declined with time, whereas hydranencephaly, arthrogryposis and cerebellar hypoplasia developed at 7 days PI and gradually progressed until 13 days PI.     

利用TMV—U1作为载体表达鼠肝炎病毒S糖蛋白片段

为了验证转基因烟草中表达的外壳蛋白（ＣＰ）能够重新包被侵入的烟草花叶病毒（ＴＭＶ）的假设,利用抗原表位标记的方法观察ＣＰ亚单位在病毒５′端的交换。通过ＰＣＲ 方法将来源于鼠肝炎病毒（ＭＨＶ） Ｓ蛋白的两个小肽段（１１ ａ．ａ．和１５ ａ．ａ．）的ＤＮＡ序列分别插入ＴＭＶ－Ｕ１ ＣＰ基因邻近３′端的两个位点,并构建了带有外源序列的ＴＭＶ 侵染克隆Ｖ９ （１１ ａ．ａ．）和Ｅ１５ （１５ ａ．ａ．）。通过体外转录反应,得到Ｖ９ ＲＮＡ 及Ｅ１５ ＲＮＡ。突变病毒ＲＮＡ 侵染烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ ）后表现不同特性。Ｖ９ 和Ｅ１５ 侵染ＸａｎｔｈｉＮＮ烟草后同野生型ＴＭＶ一样产生枯斑。但是,当它们侵染Ｘａｎｔｈｉｎｎ 烟草时,Ｖ９ 产生同侵染ＸａｎｔｈｉＮＮ 烟草相同的枯斑,而Ｅ１５的特性同ＴＭＶ－Ｕ１几乎完全相同,能对Ｘａｎｔｈｉｎｎ 烟草进行系统侵染并在叶片中聚集大量的带有外源片段的外壳蛋白,而且病毒的结构极其稳定。Ｖ９ 和Ｅ１５ 特性的差异可能是由于外源片段在外壳蛋白中存在位置的不同影响了外壳蛋白的结构所致     

Consistent handedness of microtubule helical arrays in maize and Arabidopsis primary roots

Summary The orientation of cortical microtubules in plant cells has been extensively studied, in part because of their influence on the expansion of most plant cell types. Cortical microtubules are often arranged in helical arrays, which are well known to occur with a specific pitch as a function of development or experimental treatment; however, it is not known if the handedness of helical arrays can also be specified. We have studied the handedness of helical arrays by using Vibratome sectioning of maize primary roots and confocal microscopy of Arabidopsis primary roots. In cortical cells of maize roots, the helical array was found to have the same handedness at a given position, not only for the cells of a single root, but also for the cells of more than one hundred roots examined. Quantification of angular distribution of apparent individual microtubules showed that defined regions of the root were composed of cells with highly uniform microtubule orientation. In the region between transverse and longitudinal microtubules (5–10.5 mm from the tip), the array formed a right-handed helix, and basal of cells with longitudinal microtubules (11.5–15 mm from the tip), the array formed a left-handed helix. Similarly, in epidermal cells of Arabidopsis roots right-handed helical arrays were found in the region between transverse and longitudinal microtubules. These results suggest that, in addition to the orientation of microtubules, the handedness of helical microtubule arrays is under cellular control.Abbreviations Cy3 indocarbocyanine - PBS phosphate-buffered saline - PIPES piperazine-N,N-bis-[2-ethanesulfonic acid]     

Development of PCR markers linked to resistance to wheat streak mosaic virus in wheat

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (Acer tulipae), is an important disease of wheat (Triticum aestivum L.) in the North American Great Plains. Resistant varieties have not been developed for two primary reasons. First, useful sources of resistance have not been available, and second, field screening for virus resistance is laborious and beyond the scope of most breeding programs. The first problem may have been overcome by the development of resistance to both the mite and the virus by the introgression of resistance genes from wild relatives of wheat. To help address the second problem, we have developed polymerase chain reaction (PCR) markers linked to the WSMV resistance gene Wsm1. Wsm1 is contained on a translocated segment from Agropyron intermedium. One sequence-tagged-site (STS) primer set (WG232) and one RAPD marker were found to be linked to the translocation containing Wsm1. The diagnostic RAPD band was cloned and sequenced to allow the design of specific PCR primers. The PCR primers should be useful for transferring Wsm1 into locally adapted cultivars.This is Journal Series No. J-4041 of the Montana Agricultural Experiment Station     

Inheritance of resistance to potyviruses in Phaseolus vulgaris L. IV. Inheritance, linkage relations, and environmental effects on systemic resistance to four potyviruses

We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv Great Northern 1140 (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.